• Dr Jon Barrett, Royal Holloway, University of London
  • Dr Terry Rudolph, Imperial College London 

Collaborator: Dr Rob Spekkens, Perimeter Institute

Ontological (hidden variable) models and quantum information processing

Classical information processing can be thought of as a manipulation of “local hidden variables”, except that they are typically not actually hidden! Understanding the difference in performance of quantum information processing from its classical counterpart can be attacked from the viewpoint of trying to understand the restrictions on hidden variable models – more generally called now “Ontological Models” (the word ontic pertaining to “what is real”) – in reproducing the predictions of quantum mechanics. The most famous know restriction is that such models must be nonlocal – this is Bell’s Theorem. The primary other thing we know Is that such models must be contextual – this is the Kochen Specker theorem. This latter theorem is less well understood and appreciated than Bell’s theorem. Roughly speaking it says that there must be a mathematical redundancy in any ontological model which reproduced quantum mechanics. Something which quantum mechanics describes compactly must, in some sense, blow up in its ontological model description.


A recent ontological account of measurement statistics for a qubit